Chemical Engineering - Heat Transfer - Discussion
Discussion Forum : Heat Transfer - Section 2 (Q.No. 26)
26.
For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, NPr = Prandtl number)
Discussion:
13 comments Page 2 of 2.
Sai prasad said:
7 years ago
The ratio of Prandtl number says that it is the ratio of the hydrodynamic boundary layer or momentum diffusivity to the thermal boundary layer or thermal diffusivity.
So, therefore pr=momentum diffusivity/thermal diffusivity
And when the pr number is reciprocal ie is hydrodynamic boundary layer/thermal boundary layer.
And pr no=1 means x=xt.
So, x/xt=pr*1.
X=xt*pr.
Therefore clearly it is when pr^-1 it is xt/x.
So, therefore pr=momentum diffusivity/thermal diffusivity
And when the pr number is reciprocal ie is hydrodynamic boundary layer/thermal boundary layer.
And pr no=1 means x=xt.
So, x/xt=pr*1.
X=xt*pr.
Therefore clearly it is when pr^-1 it is xt/x.
Vishwaraj said:
6 years ago
The correct answer is D. I too agree.
Anuj said:
1 year ago
The Correct answer is Npr^-1/2.
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